Process for producing fully gelatinized hulled oats

ABSTRACT

A process for producing fully and uniformly gelatinized hulled oats comprising the steps of: 
     (i) adding water to the oats; and 
     (ii) subjecting the moist oat product of step (i) to sufficient temperature and pressure for a suitable period of time to cause full and uniform gelatinization of the oats.

THIS INVENTION relates to processing of oat products and in particularto processes of preparing oat products for subsequent use such as humanconsumption.

The invention has been devised particularly, although not necessarilysolely, for preparing oat products for use as cold or hot breakfastcereals, instant snacks, instant cereal drinks, and as ingredients inbiscuits and cooking generally, baby food products, pasta, noodles andin various other known applications for oat products.

Oats have traditionally been used as a hot breakfast cereal in the formof oatmeal or porridge. However, in many homes and public dining placesit is not served due to the considerable time required for itspreparation and the subsequent cleaning of the utensils. Furthermore,once prepared oatmeal has poor keeping qualities and tends to becomepasty and undesirable in a relatively short period of time.

Recent medical reports have shown that oat bran is capable of loweringcholesterol in humans. In addition, oat bran is a highly nutritiousproduct, both in terms of possessing outstanding water soluble fibrelevels and the richness of its protein, mineral and lipid content.

Generally the stability of oat products is reliant upon the inhibitionand avoidance of enzymatic and oxidative reactions which may occur whenthe grain is damaged. While heating may seem a straightforwardalternative to deactivate the enzymes, some processing techniques havebeen found to aggravate the enzymatic and oxidative reactions. Forexample, some heat treatments are capable of inhibiting the enzyme, butaccelerate the oxidative rancidity development. Enzymatic reactionsinvolving, for example, lipolytic enzymes occur relatively slowly at lowmoisture and low temperature, and unless inactivated, or removed, thesereactions may lead to rancidity by the production of large quantities offree fatty acids. The rate of rancidity development is reported to beaccelerated by high moisture levels and by high temperatures.Furthermore, the rancidity of oats, atributable to oxidation, can occureven more rapidly under low-moisture and high-eat conditions.

deactivate active enzymes in oat bran (eg lipase and tyrosinase),involves steaming the hulled oats in the presence of heat (eg 100° C.)for 1 to 3 hours.

Further harsh heat treatment of hulled oats leads to the destruction ofantioxidants and shortening of the shelf life of the finished product.

If, for example, stabilised hulled oats are microwaved, they achieve avery desirable characteristics for consumption including a crispytexture, a smooth feel in the mouth, and a nutty flavour and aroma, butwill become rancid within a few weeks in hot weather.

Most products made from stabilised hulled oats are flaked and eaten asvarious forms of cooked porridge, mueslis or muesli bars. The flakedoats have a raw chewy texture and retain the chewiness even aftertoasting. This rawness is most probably the single-most important reasonwhy oats have not become more prominent in the cereal market.

Some products have been made from hulled oats, without first stabilisingthe enzymes. Such techniques usually involve boiling the hulled oats inwater. This partially gelatinises the starches (see U.S. Pat. No.4,413,018). However, no development has taken place to develop asuitable fully uniformly gelatinised hulled oat grains.

The major reasons behind the fact that oat products were not developedfrom gelatinised hulled oat grain was, firstly, that the properties andbenefits of evenly and fully gelatinised hulled oat grain were notknown, studied or understood. Secondly, no processes were discovered todry the gelatinised hulled oat grain in a manner which retains thestructure of the grain suitable for down stream processing. Thirdly, noprocesses were discovered to prepare the gelatinised hulled oat grainfor flaking into a ready to eat cereal or stretched into a biscuit typematerial. Fourthly, the traditional way of oat usage was asporridge-type hot cereal.

The present invention provides a process to fully and uniformlygelatinise hulled oats in a manner rendering the product suitable forfurther processing such as into cold and hot cereals. The invention alsoprovides processes for preparing a range of ingredients for breakfastcereals, snacks, baking, cooking, baby foods, pasta, noodle and otherrelated products using the fully and uniformly gelatinised hulled oats.

The present invention consists in a process for producing fully anduniformly gelatinised hulled oats are translucent in appearance and ofuniform brown colour, the process comprising the steps of. (i) by addingwater to the oats; and (ii) subjecting the oat product of step (i) tosufficient temperature and pressure for a suitable period of time tocause full and uniform gelatinisation of the oats.

The quantity of water added to the pressure vessel varies according tothe intended application or further processing stage of the gelatinisedhulled oats. However, an added water content of about 1 to 50 percent ispreferred. Typically the water content is about 6 to 25 percent.

Lighter and darker colours are possible by varying the amount of waterused, the temperature of the added steam, the cooking pressure and thecooking time

Additives such as sugar, salt, malt, non-volatile flavouring, spices orany other food ingredient capable of enhancing flavour, taste, texture,mouth feel, flaking properties may be added before or during thepressure cooking stage.

Removal of surface moisture and slight drying is achieved after thecooking by contacting the oats with air. The air is preferably warm air,but at a temperature which does not alter the surface structure of theoats.

Retention time is then allowed to achieve moisture equilibrium of thegelatinised hulled oat.

More particularly, of the invention consists in a process of preparinghulled oats to achieve full and uniform gelatinisation thereofcomprising the steps of. cooking moist hulled oats under pressure in anenvironment containing steam for a suitable period of time to cause fulland uniform gelatinisation of the oats; contacting the oats aftercooking thereof with air to initiate drying thereof and to removesurface moisture on the cooked oats; and allowing the drying process tocontinue before further processing of the oats until such time as theoats have a substantially uniform moisture content through theirstructure.

Full and uniform gelatinisation may be achieved at a range of differenttemperatures and pressures. Preferably, the oats are uniformly heatedutilising steam at a temperature of about 100° C. to 180° C., and morepreferably at a temperature of about 110° C. to 140° C. It will beappreciated that the oats may be uniformly heated by methods other thansteam which are well known in the art.

The process of the invention is also carried out under pressure.Preferably that pressure is in the order of about 0.5 to 5 bar.Typically the cooking process is carried out under a pressure of about1.5 to 3 bars.

The actual time required to achieve a full and uniform gelatinisedproduct will depend on the moisture level of the oat variety, pressurevessel size and design, quality of steam, temperature control and thedesired colour of the finished product. Be that as it may, the cookingprocess should take place for about 10 to 120 min. Preferably, theactual time is about 1.5 to 80 min and more preferably 20 to 40 min.

The fully and uniformly gelatinised hulled oats may then be processed inone of several possible further processing stages.

In one further processing stage, the gelatinised hulled oats are furtherdried under the influence of heat, retained to allow moistureequilibrium, still further dried under the influence of heat and cooledthereafter to ambient temperature. The process of gradually and gentlyremoving moisture after the steaming process, preserves the antioxidantsin the product and gives it a very special aroma, texture, mouth feeland water absorption capacity.

The dried gelatinised hulled oats have various uses, for example, thedried hulled oats can be:

(a) used as a quick cooking cereal;

(b) processed further to make a meal for an instant drink or baby food;

(c) microwaved and coated for an instant snack;

(d) be toasted and coated for an instant snack; or

(e) puffed and coated for an instant snack.

Additionally, the dried gelatinised hulled oats may have oat branextracted by traditional methods with refined oat flour as a by-product.

Shelf lives of dried oaten products like other oil containing food itemsincluding cooking oils are largely influenced by their antioxidantcontents. When the antioxidants are used up, even in only portion of agrain product the onset of rancidity follows rapidly, the speed beingtemperature influenced. The data presented in U.S. Pat. No. 4,413,018shows that it is easy to produce material which shows destabilisationdue to accelerated oxidative rancidity. Boiling or steaming oatsfollowed by drying with various air jet drying regimes shows thatincreasing the drier time or increasing the drier temperaturedestabilises the products. Similarly processing oats merely by the useof jet drier alone shows that the harsher the total thermal treatmentthe more likely the appearance of oxidative rancidity. When drying theproduct of the present invention, drying should be achieved by the useof lower drier drying temperatures used for short periods followed byrest periods to permit moisture movement from the relatively damperinterior to the drier surface regions of the grain, followed by repeateddrying--resting cycles until the grain moisture content has reached alevel which ensures microbiological safety.

The treatment prescribed by the above drying process when strong enoughgives a grain which has a pleasant chocolate aroma. This nonartificially added aroma has not been reported before in oaten products.

While the people do not normally eat straight dry oaten groats it hasbeen found that dried fully and uniformly gelatinised oat products cookreadily in boiling water for 10 to 15 minutes give a nutty flavoured,chewy product similar but more nutritious than cooked brown or whiterice. The taste and texture while similar to rice are not identical andso increase the variety of cooked grain products available to peoplewishing to carry out the dietary recommendations given around the worldto eat more or to ensure a significant part of one's diet consists ofwholegrain products.

In another further processing stage, the fully and uniformly oat groatgelatinised may be steamed and flaked. This provides ready-to-eatinstant flakes or the flakes may be coated and toasted for other uses ina conventional oven. The flaking process results in a flake with aunique texture, taste, aroma, mouthfeel and is suitable as either a hotor cold cereal.

Fully and uniformly gelatinised groats retaining a minimum of 20%moisture after the gelatinising process may be flaked by conventionalmilling methods using for example a one to one gear ratio and 300 mmdiameter rollers on a flaking machine. After flaking the product-ispreferably dried to a moisture content of about 10 to 12%.

The flakes produced by this method are unique and different fromtraditional oats. Traditional oat flakes are white to slight goldencolour, floury in texture, raw when chewed and with no aroma. They aretypically used as a hot cereal whereby one needs to cook them from 2 to10 minutes before eating.

Fully and uniformity gelatinised groats when used in the describedflaking process produce a totally new and unique flake not previouslyassociated with oats. The flakes are of a light amber appearance andwhen broken little white starch is visible. They have a biscuity textureand slight malty aroma. They are no longer raw and can be eaten dry orwith liquids, hot or cold. There are a lot more water absorbent thantraditional oat flakes so they will cook a lot faster for the same flakethickness.

In still another further processing stage fully and uniformlygelatinised hulled oats may be steamed and stretched to provide, forexample, biscuit-type flakes, ready for compressing into a biscuit formand baking. The stretched flakes are also coated and toasted in a streamof hot air to give a flake similar to wheat or corn. The stretch flakingprocess also results in a Fake with a unique texture. taste, aroma, andmouthfeel for cold cereal and biscuits.

Fully and uniformly gelatinised groats retaining a minimum of 25%moisture after the gelatinising process may be stretch flaked byconventional milling methods using for example a differential gear ratioand 300 mm diameter rolls on the flaking machine.

After flaking the product is toasted in conventional ovens, cooled andpackaged into retail packs, or alternatively compressed into rectangularbiscuits, toasted in conventional ovens, cooled and packaged into retailpacks.

The flakes produced by this method are unique and different fromtraditional oats. Traditional oat flakes are white to slight goldencolour, floury in texture, raw when chewed and with no aroma. They aretypically used as a hot cereal whereby one needs to cook them from 2 to10 minutes.

Fully and uniformly gelatinised groats when used in the describedstretch flaking process produce a totally new and unique flake notpreviously associated with oats. The flakes are of a light amber andtranslucent appearance and when broken, little white starch is visible.They have a biscuity texture and a slight malty aroma. They are nolonger raw and can be eaten dry or with liquids, hot or cold. They are alot more water absorbent than traditional oat flakes so they will cook alot faster for the same flake thickness. When compressed and formed intorectangular biscuits and toasted, they produce a truly biscuity texturedbix (breakfast biscuit) not previously associated with oat product.

By uniformly and completely gelatinising starches in hulled oats by theprocess according to the invention, a new range of oat products withvery desirable nutritional and marketing properties, can be produced.

The major part of food energy in vegetable material normally is in theform of starch. However, for people to obtain the complete benefit ofthis starch It must be first digested by starch splitting enzymes (egamylolytic enzymes) to convert the starch first to oligosaccharides andthen to simple sugars. It is the simple sugars which the body canactually absorb. Before the amylolytic enzymes are able to function theymust actually reach the starch. However the starch Is stored in starchgranules which are surrounded by a wall which the starch splittingenzymes cannot penetrate. The starch granule wall has to be brokenbefore effective digestion can start.

Starch granules are susceptible to mechanical damage during grinding andmilling which changes some properties of the oat product but only whenheated in the presence of moisture. The process by which the granulesabsorb water, swell and burst is recognised as gelatinisation. Accordingto the present invention, the extensive exposure to damp heat duringgelatinisation leads to complete deactivation of all the enzymesinvolved in reducing shelf life--the lipase and peroxidises.

Fully uniform gelatinisation of the oat product enables more completeutilisation of the oat grain. This involves the recommended complexcarbohydrates, which have a valuable role in maintaining health. Theincreased digestibility makes the products produced as a result of theinvention an ideal ingredient for infants, children and people withdigestive problems.

The significant amount of starches made available in the oat products ofthe present invention may also be converted to resistant starches.Resistant starches by not being digested until the food reaches thelarge intestine has some of the properties of dietary fibre and isconsidered to add in preventing colon cancer. Overall the effectivedietary fibre content rises from approximately 11% of the conventionallyprocessed oats up to around 19% by use of the present invention

Oat products produced from processes according to the invention haveimproved properties in comparison to the oat products provided accordingto prior art processes. The improved properties include the following:

(1) Greater resistance to oxidative rancidity.

This is conducive to application in microwaved instant snacks andproducts subjected to high process temperatures eg. extrusion, bakingetc

(2) Improved shelf life.

It is believed that the shelf life will improve by 60% to 100% ontraditional oat products. This has application across the whole spectrumof oat products.

(3) Improved digestibility.

This is conducive to application in baby cereals, hospital diets,nutritional snacks, performance products.

(4) Can increase in the overall effective dietary fibre content byapproximately 70%.

This is conducive to application in nutritional product aiming atcholesterol reduction, diabetic foods, cereals with a high nutritionalprofile.

(5) Significantly higher viscosity.

This will improve performance in extrusion and wherever bindingproperties are required.

(6) Significantly higher water absorptivity.

This is conducive to application in instant drinks, bread making,baking, instant cereals, cold cereals.

(7) Improved texture, aroma and taste.

This is conducive to application in hot and cold cereals, biscuits,flakes, flour, bran, roasting and toasting.

According to a second aspect the invention provides a fully anduniformly gelatinised oat product produced by mixing water with hulledoats and then subjecting the moist oat to sufficient temperature andpressure for a suitable period of time to cause full and uniformgelatinisation of the product.

According to a third aspect of the invention there is provided an oatproduct characterised in that the starches thereof are fully anduniformly gelatinised.

The invention will be better understood by reference to the followingdescription of several specific examples.

It will be understood that all ranges of temperature, pressure, time andmoisture levels prescribed in the various examples are given asindicative only, and that parameters outside these limits may alsoprovide useful results.

In the description, percentage moisture is given on a dry weight basisand all additives are given as percentage weight.

EXAMPLE 1

This example is directed to processing of hulled oats (either enzymestable or green) to produce a fully and uniformly gelatinised hulledoats product. The process provides the product of the invention using asteam cooking process with minimum addition of water, and a gradualdrying after full gelatinising has been reached.

The steam cooking process is performed in a pressure vessel so designedthat the product exposure to steam and the steam distribution are bothvery uniform. Typically, 6 to 12% of water is added to the hulled oatsfor the cooking process. With such an arrangement steam is used as theheating and pressurising medium. The cooking process is carried outunder a pressure of about 1.5 to 3 bar.

The temperature range is from about 110° C. to 140° C. and the oats arecooked in the pressure vessel for between about 20 and 40 minutes.

The actual time required depends on moisture level, oat variety,pressure vessels size and design, quality of steam, temperature controland the desired colour of the finished product.

Other ingredients such as malt, sugar, salt, non volatile flavouring,spices or any other food ingredient capable of enhancing flavour, taste,texture, mouth feel, flaking or binding properties, are added beforeand/or during the pressure cooking stage.

The cooked product is fully and uniformly gelatinised when it is totallytranslucent and of a uniform brown colour. No white streaks should bevisible and the cross-section is fully gelatinised without any trace ofchalky white endosperm.

Once full gelatinisation has occurred, the product is released from thepressure vessel and a process of gradual uniform moisture reductionbegins. During this stage in the process the product is gradually driedby uniformly blowing warm air (at about 40 to 50° C.) through theproduct for a period of about 20 to 60 minutes. The length of timerequired to reduce the moisture in the product will be dictated by themoisture content required in the fully and uniformly gelatinised oatproduct. Gentle moisture reduction is necessary as the heat used inmoisture removal in some of the products produced using the inventionalters the structure of the outer layers to the detriment of down-streamprocessing. It also depletes the anti- oxidants and thus reduces theshelf-life of the finished product.

Minimal steaming regimes found to achieve complete and uniformgelatinised oaten groats are exemplified in the following table.(Starting material--hulled Mortlock oats of circa 10% moisture, grown inWestern Australia):

    ______________________________________                                                                      AMOUNT                                          TIME PRESSURE PRESSURE        OF ADDED                                        COOKING IN MINUTES                                                                          TEMPERATURE     WATER                                           ______________________________________                                        25            260 kpa/144 degrees C.                                                                        10%                                             19            245 kpa/138.5 degrees C.                                                                      15%                                             15            210 kpa/135 degrees C.                                                                        40%                                             20            210 kpa/135 degrees C.                                                                        20%                                             30            219 kpa/135 degrees C.                                                                        10%                                             40            160 kpa/129 degrees C.                                                                        15%                                             60            110 kpa/122 degrees C.                                                                        20%                                             ______________________________________                                    

Gelatinisation was determined by change in the appearance of theendosperm of the cut groat Such changes had previously been checked toensure this correlation by having the degree of gelatinisation checkedby being placed in a fixative solution for four days, then sectioning ona cryostat microtome, stained with selected histochemical reagents (egiodine) and examined under a high powdered microscope.

As would be expected the gelatinisation process which involves theswelling of the starch granules in the grain to past bursting point istime, temperature and moisture dependent. The greater the moisture andthe higher the temperature the faster the water will move into thegranules.

EXAMPLE 2

This example provides a fully and uniformly gelatinised hulled oatproduct that may be used as groats, kibble groats, bran and flour.

The method of example 1 was repeated. The resultant product was thenpneumatically conveyed to and retained in a Stainless Steel Bin whereinsweating of the product was allowed to occur. The groat was then passedon to a retention belt for between 1 and 4 hours. This allows a uniformmoisture distribution to take place. Moisture levels of about 15 to 18%are achieved in this stage.

The second stage involves drying with hot fluidising air (about 60° C.to 80° C.) for about 10 to 15 minutes. Alternatively an infra-red driermay be used. The product is then retained in a Stainless Steel bin forabout 1-2 hours to allow a uniform moisture distribution to take place.Moisture levels of 12 to 15% are obtained in this stage.

The third stage involves a single-step drying and cooling procedure withfluidising hot and ambient air. Alternatively, infra-red drier with asurface coater is used, followed by cooling with ambient air. Maximummoisture level after this stage is 12%.

The product obtained from this process has a very smooth texture,biscuity taste, and nutty aroma. The product can be puffed in amicrowave to give an instant snack. The product is very water absorbentand after grinding will give an instant cereal drink which is aromaticwith biscuity flavour and texture.

The finished products cooking time is close to most rice varieties andIts texture after cooking resembles that of rice, it therefore is anideal ingredient in a rice mixture.

Due to its reduced cooking time, the product is an ideal ingredient forsoups.

EXAMPLE 3

This example is directed to processing of green hulled oats to producegelatinised hulled oats as flakes.

The process provides an oat flake by first fully and uniformlygelatinising green hulled oat grains, flaking, drying and cooling theproduct.

The process incorporates uniform gelatinising of hulled oats in a steamcooking process using a pressure vessel similar to the one used forExample 1 with sufficient water addition to enable flaking. Typically,about 20% to 30% of water is added to hulled oats in this example.

In the cooking process, the hulled oats are pressurised at about 1.5 to3 bar pressure using steam as heating and pressurising medium.

The temperature range is from about 110° C. to 140° C. and the cookingprocess in the pressure vessel proceeds for between about 20 and 40minutes. The actual time required depends on moisture level, oatvariety, pressure vessels size and design, quality of steam, temperaturecontrol and the desired colour of the finished product.

As with Example 1, other ingredients such as malt, sugar, salt, nonvolatile flavouring, spices or any other food ingredient capable ofenhancing flavour, taste, texture, mouth feel, flaking or bindingproperties, are added before and/or during the pressure cooking stage.

Once full gelatinisation is achieved, the product is released from thepressure vessel.

Moisture is then partially removed by blowing warm air (at about 40 to50° C.) through the product for about 20 to 60 minutes.

The moisture level after this stage of the process is about 25 to 35%.

The product is then steamed in a conditioner or steaming column andflaked using conventional oat flaking roller. A roller having a rolldiameter of a minimum of 500 mm and a single gear ratio is particularlysuitable. Alternatively the product may be prepared using the sameprocess, but without the steaming process.

A range of flake thickness is produced from 0.2 mm to a slightly bumpedproduct.

The product is then dried to a maximum of about 12% moisture and cooledto ambient temperature. This can be achieved by subjecting the productto hot and cold fluidising air. Alternatively, the drying may beperformed by an infra-red drier and subsequent cooling by ambient air.

The flakes obtained from this process are unique in its texture, taste,mouth feel, liquid absorption, aroma and appearance.

They have a natural advantage in almost all areas where conventional oatflakes are used.

EXAMPLE 4

This example is directed to processing of green hulled oats to producegelatinised hulled oats as stretched flakes.

This process provides a stretched oat flake by fully and uniformlygelatinising green hulled oat grain, flaking, drying and cooling theproduct.

The process incorporates uniform gelatinising of hulled oats in a steamcooking process using a pressure vessel similar to the one used forExample 1 with sufficient water addition to enable flaking. Typically,about 25 to 40% of water is added to the hulled oats in this example.

As with Examples 1 and 2, the hulled oats are pressurised in the cookingprocess at about 1.5 to 3 bar pressure using steam as the heating andpressurising medium.

The temperature range is from about 110° C. to 140° C. and the cookingprocess in the pressure vessel proceeds for between about 20 and 40minutes. As with the earlier Examples time required depends on moisturelevel, oat variety, pressure vessels size and design, quality of steam,temperature control and the desired colour of the finished product.

As with Examples 1 and 2 other ingredients may be added before and/orduring the pressure cooking stage.

Once fully gelatinisation has occurred, the product is released from thepressure vessel.

Moisture is then partially removed by blowing warm air (at about 40 to50° C.) through the product for about 20 to 60 minutes.

The new moisture level after this stage of the process is about 30 to45%.

The product is then steamed in a conditioner or steaming column andflaked. Preferably, the flaking stage is performed using chilled wallsflaking rollers with a minimum 500 mm dia. rolls and a differential gearratio. Alternatively the product may be prepared using the same process,but without the steaming process.

A fine flake thickness is produced from about 0.1 mm to 0.2 mm.

The stretched oat flakes are either coated and toasted, or made into abiscuit and baked in an oven.

The stretched oat flakes are toasted in a hot air stream to give auniform toasting and partially blister the surface.

The stretched oat flakes are compressed with rollers and formed in a 15to 20 mm bed on a wide conveying tray. Rectangular shapes are cut on thetray, the product fed into a conventional biscuit oven.

The products made from stretched oat flakes are unique in taste,texture, aroma and mouth feel and will be able to compete with thetraditionally made wheat and corn flakes as well as with the wheatbiscuits.

EXAMPLE 5

Investigation of viscosity properties of products made from the presentinvention versus conventional oaten products (all made from WesternAustralian grown Mortlock oats) using a New Port Scientific RBA-3Dviscometer.

Each of the oaten products were mixed with water (65° C.) 4 g in 25 mlwater and left for 2 minutes. The temperature of the mixture was thenraised quickly to 95° C. After nine minutes the temperature of themixture was gradually reduced to 50° C. (took approximately 12 minutes).Then gradual temperature was stopped after a further 15 minutes.

Viscosity is expressed in stirring number units SNU, to convert tocentipoise multiply by 9.75.

    ______________________________________                                                                    Maxi-                                             Peak               Holding  mum   Final Peak                                  vis-       Peak    viscosity                                                                              Setback                                                                             Setback                                                                             viscosity                             cosity     time    (SNU)    (SNU) (SNU) Final                                 (SNU)      (mins)  (95° C.)                                                                        (50° C.)                                                                     (50° C.)                                                                     Setback                               ______________________________________                                        Fully and                                                                            294     5.5     202    482   482   0.61                                uniformly                                                                     gelatinised                                                                   Whole- 285     5.5     198    473   472   0.60                                meal                                                                          oat flour                                                                     Instant oat                                                                          300     5.4     187    450   450   0.67                                drink base                                                                    (ground                                                                       through a                                                                     2 mm                                                                          screen)                                                                       Instant                                                                              290     5.4     185    445   445   0.65                                rolled oats                                                                   (ground                                                                       through a                                                                     2 mm                                                                          screen)                                                                       Instant oat                                                                          302     5.4     191    470   470   0.64                                drink base                                                                    (produced                                                                     from fully                                                                    and                                                                           uniformly                                                                     gelatinised                                                                   oats)                                                                         Instant                                                                              278     5.5     180    447   447   0.62                                rolled oats                                                                   ______________________________________                                    

As can be seen there is always a higher viscosity seen in the oatenproducts which have been subject to the gelatinisation process of thepresent invention. This however is not as high as expected and thereexists the possibility that the high amount of beta-lucan found inMortlock oaten kernels (average 4.7% on a dry weight basis) could beinterfering with the gel-matrix being formed in solution by the starchof the oats. Thus the difference in solution viscosity betweenconventional and oat products produced from the present invention willalmost certainly be greater when cultivars with lower levels ofbeta-glucan are utilised.

EXAMPLE 6

Investigation into the properties of solutions made using oaten materialwhich has been subject to the method of the present invention using aNew Port Scientific RBA-3D viscometer.

In order to obtain a suitable thick or viscous drink to satisfy customerexpectations for certain instant and quick dissolving drink productscertain attributes are required. The solutions must not only be thickenough, they must also hold their viscosity for a reasonable length oftime.

All samples were run with 4 g of ground oats (ground through a 0.5 mmscreen) in 25 mls of water. Solutions were made up at room temperatureor 60° C. where necessary and cooled back to room temperature wherenecessary.

Viscosity is expressed in stirring number units (SNU), to convert tocentipoise multiply by 9.75.

Cooled sample had a viscosity of 63

    ______________________________________                                        SOLUTION TEMPERATURES AND TIME (IN HOURS) VERSUS                              VISCOSITY SOLUTION                                                            0 HR  SNU    1 HR    SNU   3 HRS SNU   6 HRS SNU                              ______________________________________                                        RT    78     RT      161   RT    170   RT    150                              60° C.                                                                       106    RT      194   RT    192   RT    165                              60° C.                                                                       106    60° C.                                                                         87    RT    154   RT    137                              60° C.                                                                       106    60° C.                                                                         93    60° C.                                                                       65    RT    114                              60° C.                                                                       106    60° C.                                                                         91    60° C.                                                                       63    60° C.                                                                       39                               ______________________________________                                         RT = room temperature circa 25° C.                                

Thus for the better effect in the short term it is preferable to make updrinks with hot (60° C.) rather than cool (25° C.) water. While asolution made with cool water improves with time it still does not matchthat made up with hot water and then allowed to cool. However, keepingthe solution at 60° C. resulted in a poorer drink product than if thehot drink was allowed to cool. That is samples heated to 60° C.decreased in viscosity with holding at that temperature, but became moreviscous when the temperature was reduced to room temperature.

The viscosity of the heated drink allowed to cool remained stable for atleast three hours.

Samples held at room temperature increased in viscosity over three hoursbut then began to decline possibly due to enzymatic breakdown.

EXAMPLE 7

Resistant Starch in products produced from the present invention andconventional products:

Using the Megazyme method of resistant starch measurement, which givesthe difference of total starch and "available" or enzymaticallydigestible starch. Data is expressed on a dry weight basis. The termslow cooling refers to the period after the hot pressure steam treatmentwhether the groats were permitted to remain in the steaming vessel for aperiod of approximately 8 hours or more.

    ______________________________________                                        Oaten Sample        Resistant Starch Content                                  ______________________________________                                        Fully and Uniformly Gelatinised groats                                                            4.6%                                                      non slow cooling                                                              Fully and Uniformly Gelatinised groats                                                            8.4%                                                      slow cooling                                                                  Fully and Uniformly Gelatinised groats                                                            8.9%                                                      slow cooling                                                                  Porridge Oats       2% (published result)*                                    ______________________________________                                         *Englyst H N, Kingman, S M and Cummings J H  Classification and               measurement of nutritionally important start fractions. European Journal      of Clinical Nutrition, 1992, volume 46. Supplement 2, S33-S50.           

The higher level of resistant starch in the slow cooled sample is notunexpected as resistant starch is due to crystallised starch chainswhose crystallisation development is dependent on temperature, starchconcentration and moisture concentration (sufficient moisture must bepresent for chain movement and rearrangements to take place). Thepublished result refers to a product which has been more processed thanmere groats however the extra processing should only increase the amountof resistant starch present so the contrast seen above in the amountsbetween a conventionally processed product and the fully and uniformlygelatinised treated products is almost certainly in reality greater thanthis.

An advantage of increasing the amount of resistant starch in oatenproducts is that this raises their actual dietary fibre contents.Resistant acts as a dietary fibre in that it is not digested in thesmall intestine by the persons own enzymes but is able to be digested bybacterial enzymes in the large intestine. Resistant starch is consideredto help prevent colon cancer, possible mechanisms for this include byproduction of short chain volatile fatty acids such as propionic andbutyric acids due to bacterial digestion or possibly by increasingfaecal bulk. Overall the effective dietary fibre content for fully andunfirmly gelatinised treated Mortlock wholemeal oaten products goes fromapproximately 11% to around 19%

EXAMPLE 8

    ______________________________________                                        Appearance of Chocolate Aroma under different treatment regimes               in stored fully and uniformly gelatinised oats and other oaten groats         Time of                                                                       Pressure Pressure of         Temperature                                                                           Developed                                Cooking in                                                                             Cooking in                                                                              Amount of of fluid bed                                                                          Chocolate                                minutes  kpa       added water                                                                             drier   Aroma                                    ______________________________________                                        Kilned groats                                                                          atmospheric                                                                              0%       --      no                                       Boiled groats                                                                          atmospheric                                                                             200%      110° C.                                                                        no                                        5       atmospheric                                                                             200%      110° C.                                                                        no                                       10       atmospheric                                                                             200%      110° C.                                                                        no                                       15       atmospheric                                                                             200%      110° C.                                                                        no                                       30       atmospheric                                                                             200%C     110° C.                                                                        no                                       ______________________________________                                    

    ______________________________________                                        Pressure                                                                      cooked groats                                                                 ______________________________________                                        60          110 kpa 20%      50° C.                                                                        no                                        30          150 kpa  0%      60° C.                                                                        faint                                     30          150 kpa  0%      60° C.                                                                        faint                                     45          150 kpa  0%      60° C.                                                                        some                                      40          160 kpa 15%      50° C.                                                                        no                                        15          180 kpa  0%      60° C.                                                                        no                                        10          210 kpa 10%      50° C.                                                                        no                                        10          210 kpa 10%      50° C.                                                                        no                                        15          210 kpa 40%      50° C.                                                                        faint                                     20          210 kpa 10%      50° C.                                                                        faint                                     20          210 kpa 20%      50° C.                                                                        faint                                     20          210 kpa 10%      100° C.                                                                       some                                      30          210 kpa 10%      50° C.                                                                        strong                                    30          210 kpa 10%      100° C.                                                                       slight                                    40          210 kpa 10%      50° C.                                                                        slight                                    40          210 kpa 10%      100° C.                                                                       slight                                    50          210 kpa 10%      50° C.                                                                        strong                                    90          210 kpa 10%      50° C.                                                                        strong                                    15          300 kpa  5%      90° C.                                                                        some                                      ______________________________________                                    

Chocolate Aroma

Some of the samples exhibited quite a strong chocolate like aroma afterbeing stored for a time. The phenomena appeared only in the pressurecooked grain, taking several weeks to appear, though the speed of itsappearance was faster in the samples stored at 45 degrees C. than inthose stored at room temperature. The temperature effect showing thatthis is a chemical reaction Or the result of a series of chemicalreactions. Though the intensity varied somewhat, it was roughly relatedto the length of pressure cooking.

An attempt was made to identify the volatile components(s) responsiblefor the chocolate aroma by gas chromatography-mass spectrometer(volatilise collected into glass lined stainless steel trap packed withTenax GC [Scientific Glass Engineering Pty Ltd, Australia] Gaschromatography column--Hewlett Packard, HP Innowax, helium carrier gas,introducer temperature 280° C. However the system tried did not provesensitive enough to Identify such components.

EXAMPLE 9

Investigation of the shelf life of popped groats

Popping was performed by taking approximately 200 grams of groats andplacing them in a dish in a microwave oven (approximately 600 watts) seton high and cooking for a period of 25 to 30 seconds, stopping andstirring the groats to help ensure even cooking then repeating themicrowaving, beating an stirring until all groats appeared to have beenpopped. The term green groats means that before popping the groats hadbeen physically hulled but not subjected to any heat treatments.

The shelf life testing was carried in jars and kept at approximately 45degrees C.

    ______________________________________                                                              Approximate                                                        Microwaving                                                                              Shelf Life in                                           Starting Material                                                                        period     Weeks       Notes                                       ______________________________________                                        Green Groats                                                                             130 seconds                                                                               7 to 11    some burnt                                  Green Groats                                                                             150 seconds                                                                              11 to 13    none burnt                                  Kilned Groats (3.5                                                                       130 seconds                                                                              11 to 13    none burnt                                  hours kilning)                                                                Fully and  150 seconds                                                                              greater than 56                                                                           none burnt                                  Uniformly             weeks                                                   gelatinised Groats                                                            (50 minutes                                                                   steaming)                                                                     Fully and             greater than 26                                         Uniformly             weeks                                                   gelatinised                                                                   Groats, puffed                                                                with popping gun                                                              ______________________________________                                    

Fully and uniformly gelatinised groats subjected to a long steamingprocess under pressure when popped, produce a product with a shelf lifeabout five fold or more longer than popped groats made fromconventionally kilned groats or from green groats.

As would be expected the presence of even a small amount of burnt grainis to be avoided as they will significantly shorten the shelf life of abatch of popped groats--for example, see the shelf lives of the twogreen groat samples in the above table). The decreased shelf life isalmost certainly due to the destruction of the antioxidants present inthe kernels ensuring an earlier onset of the uncontrolled radical chainreaction oxidisation of the fat present.

The pressure steaming with added water cooking of the oat groats, hasaltered the structure or nature of the cooked groats such that theproduct even when subjected to the thermal stress treatment of beingpopped has a vastly longer (perhaps over five fold longer) shelf lifecompared to popped kilned oat groats and popped green groats made fromthe same raw material.

By achieving a shelf life of more than a year, the products becomeindustrially useful (ie they can be produced packaged or incorporatedinto mixtures (eg mueslis) or incorporated into products (eg mueslibars) and distributed through the retail network (supermarkets etc) andconsumed within a reasonable time and before their shelf life isexceeded and they become rancid.

Possible mechanisms explaining the cause of the increased shelf lives ofthe popped or puffed product produced from fully and uniformlygelatinised oats might include:

(i) The formation of a hard gas impervious or semi-impervious layerhindering oxygen penetration. Quite likely as physical hindrances tooxygen penetration are important in maintaining oat products shelflives; (The Scientific Journal "Cereal Chemistry" Volume 72, pages21-24, 1995)

(ii) Mallaid reaction type antioxidant components generated during thehigher temperature (circa 120° C. and higher) achieved by processingwith steam under pressure: and/or

(iii) The processing causes the fat droplets in the groats to beabsorbed into the starch matrixes present in the groat cells and so maybe limited the oxygen access to the fat material.

It should be appreciated that the scope of the invention is not limitedto the scope of the various examples described. In particular, it shouldbe appreciated that various modifications and alterations may be madewithout departing from the scope of the invention.

The claims defining the invention are:
 1. A process for producing fullyand uniformly gelatinised hulled oats which are translucent inappearance and of uniform brown colour comprising the steps of:(i)adding water to hulled oats; and (ii) subjecting the moist oat productof step (i) to sufficient temperature and pressure for a suitable periodof time to cause full and uniform gelatinisation of the oats, whereinsaid pressure is above atmospheric pressure.
 2. A process according toclaim 1 wherein the water added to the oats in step (i) comprises 1 to50% of the moist oat product employed in step (ii).
 3. A processaccording to claim 2 wherein the water added to the oats in step (i)comprises about 6 to 25 percent of the moist oat product employed instep (ii).
 4. A process of preparing hulled oats which are translucentin appearance and of uniform brown colour and having full and uniformgelatinisation thereof comprising the steps of:(i) cooking moist hulledoats under pressure in an environment containing steam for a suitableperiod of time to cause full and uniform gelatinisation of the oatswherein said pressure is greater than atmospheric pressure; (ii)contacting the oats after cooking thereof with air to initiate dryingthereof and to remove surface moisture on the cooked oats; and (iii)allowing the drying process to continue before further processing of theoats until such time as the oats have a substantially uniform moisturecontent through their structure.
 5. A process according to claim 1wherein the temperature of step (ii) is about 100° to 140° C.
 6. Aprocess according to claim 1 wherein the pressure of step (ii) is about1.5 to 3 bar.
 7. A process according to claim 1 wherein the moist hulledoat product from step (i) is subjected to temperature and pressure instep (ii) for about 20 to 40 minutes.
 8. A process according to claim 1,further comprising steps of partially drying the fully and uniformlygelatinised hulled oats from step (ii) under the influence of heat,retaining the partially dried oats to allow moisture equilibrium, dryingagain under the influence of heat and cooling the oats to ambienttemperature.
 9. A process according to claim 1 further comprising stepswherein the fully and uniformly gelatinised hulled oats from step (ii)are steamed and then flaked.
 10. A process according to claim 1 furthercomprising steps wherein the fully and uniformly gelatinised hulled oatsfrom step (ii) are steamed and then stretch flaked.
 11. A processaccording to claim 9 further comprising a step of toasting the flakedoat products in a stream of hot air.
 12. A process according to claim 1further comprising a step wherein the fully and uniformly gelatinisedhulled oats from step (ii) are puffed.
 13. A process according to claim1 further comprising a step wherein the fully and uniformly gelatinisedhulled oats from step (ii) are puffed by heating.
 14. A processaccording to claim 1 further comprising a step wherein the fully anduniformly gelatinised hulled oats from step (ii) are microwaved forsufficient time to pop the hulled oats.
 15. A fully and uniformlygelatinised oat product produced according to the process set forth inany one of the claims 1-3, wherein said product is characterized by achocolate aroma.
 16. A process according to claim 10 further comprisinga step of toasting the flaked oat products in a stream of hot air.
 17. Aprocess according to claim 1, wherein one or more ingredients selectedfrom the group consisting of malt, sugar, salt, and spices is added tothe oats before or during the cooking step (ii).
 18. A process forproducing fully and uniformly gelatinised hulled oats, comprising thesteps of:(i) adding water to hulled oats to provide a moistened oatproduct; (ii) heating the moistened oat product at a pressure aboveatmospheric pressure, and at a temperature sufficient to steam cook theoats, for a cooking time sufficient to produce fully and uniformlygelatinised hulled oats that are translucent and of a uniform browncolour free of white streaks and free of chalky white endosperm.
 19. Aprocess according to claim 18, wherein one or more ingredients selectedfrom the group consisting of malt, sugar, salt, and spices is added tothe oats before or during the heating step (ii).
 20. A process accordingto claim 18 wherein the water added in step (i) comprises 6 to 25percent of the moistened oat product.
 21. A process according to claim18 wherein the heating step comprises heating at a pressure of 1.5 to 3bar, at a temperature of 110° C. to 180° C. for 1.5 to 80 minutes.
 22. Aprocess according to claim 18 further comprising a gradual moisturereduction, said gradual moisture reduction comprising at least twodrying steps under the influence of heat and a final period of cooling,wherein the drying steps are separated by a retaining period to permituniform moisture redistribution in the oats, and wherein said gradualmoisture reduction reduces depletion of antioxidants in the oatsrelative to a continuous heat drying procedure.
 23. A process accordingto claim 22 wherein the drying steps comprise contacting the gelatinisedoats with warmed air.
 24. A process according to claim 22 wherein aninfra-red dryer is used in the drying steps to dry the gelatinised oats.25. A process according to claim 18 wherein step (ii) is performed in asteaming vessel and wherein the fully and uniformly gelatinised hulledoats produced in step (ii) are retained in the steaming vessel for atleast 8 hours to increase enzyme-resistant starch content in thegelatinised hulled oats.
 26. An oat product produced by the method ofclaim 18, said oat product characterized by uniform and fullgelatinisation, translucence, and a uniform brown colour free of whitestreaks and free of chalky white endosperm.